1. Field of the Invention
The invention is in the field of air vehicles launched from launchers, such as powered or unpowered projectiles launched from gun tubes, launch tubes, or other launchers, with end features that could interfere with deployed surfaces of the air vehicles.
2. Description of the Related Art
Air vehicles launched from launch tubes, gun tubes, or other launchers often have fins that are used in flight to stabilize the vehicle, as well as for other purposes. The fins are stowed during launch, in order to allow the air vehicle to fit in the launcher.
Pressurized gases produced for propulsion during launch may get underneath the fins during the launch process. Near the mouth of the launcher there may be a muzzle brake or other openings which redirect pressure that is inside the launcher, for instance to reduce recoil. The pressurized gasses trapped underneath the fins may tend to push the fins outward, which is undesirable, as contact between the fins and the walls of the launcher may damage the fins and/or the launcher, and/or may adversely affect trajectory of the air vehicle.
If the launcher is rifled, so that the air vehicle spins about its longitudinal axis as part of the launch process, centrifugal forces may urge the fins outward prior to the vehicle exiting the launcher. Again premature deployment of fins would be undesirable.
In view of the above, it would be desirable to easily control fin deployment. Management of fin deployment may be accomplished by control of roll rate, internal pressurization, and fin moments of inertia, but such control puts restraint on performance.